User manual

Code: ENIGMA III User Manual
Edition: 1 Revision: 4
Date: 19/12/2008
Page: 11/97
2.1.1 Noise Power threshold
The Noise Power threshold [dB] is related to the noise floor measured through noise sampling and is
applied to reflectivity data. Typically, the noise threshold is 1 dB above the noise floor.
Parameter: NOISEThreshold
2.1.2 CCOR threshold
The clutter power threshold [dB] is compared to the clutter power, obtained from the 4. order Chebyshev
IIR high pass filter or the filtered result from the frequency domain filtering. Reflectivity data and/or
radial velocity and/or spectral width data can be thresholded, when the calculated clutter power exceeds
the clutter threshold limit.
Parameter: CCORThreshold
2.1.3 SQI threshold
The Signal quality threshold (SQI) is compared to the signal quality, resulting from autocorrelation
processing. A signal quality value of 0 represents only noise, whereas a value of 1 represents a perfect
tone (sine wave). This threshold is absolute for thresholding of Doppler moments (radial velocity and
spectral width). Typically values for thresholding are 0.4..0.5, depending on receiver input S/N ratio.
Parameter: SQIThreshold
2.1.4 RHOHV Threshold
In SIDPOL configuration the RhoHV moment can be used for thresholding. RhoHV is close to 1 for
spherical targets (water droplets) and quickly falls to lower values for other targets. A good starting value
would be 0.7-0.8
Parameter: RHOHVThreshold
2.1.5 PhiDP SNR Threshold
In SIDPOL configuration the PhiDP and the related KDP moment can be thresholded with SNR. If the
SNR of the signal is lower than the specified threshold the PhiDP and KDP moments will be thresholded.
Set threshold to 0 to disable this thresholding algorithm.
Parameter: PhidpSNR
GAMIC Proprietary